Shambling Mound -- hit with lightning, it gains CON. Does temp CON stack?

[aboyd]

Here is the shambling mound listing.

It gains temp CON if you hit it with lightning. I haven't seen any ruling on if temporary ability score increases stack, so I'm going to follow the rules for stacking temporary hit points. That is, same source = "no stacking" but different sources stack. (That's also the same rule used for spells, I think.)

Now, down to the problem. Where do I register the "source" for determining stacking? What I mean is this:

• Is the monster ability the source? In other words, any time the monster ability is triggered, it's the monster ability that is the source, and therefore nothing will ever stack, no matter what hit it with lightning.
  
• Is the thing that triggers the monster ability the source? So a wizard casts Lightning Bolt, and a storm creature zaps the shambling mound with a natural shock attack, and a fighter uses one of those alchemical bottled lightning things to deal some electricity damage too... each of those a different source?
  

Thanks for your advice.

[James Risner]

Nothing stacks with itself unless it tells you how.

The source is the monster ability.

[Starbuck_II]

aboyd wrote:

Here is the shambling mound listing.

It gains temp CON if you hit it with lightning. I haven't seen any ruling on if temporary ability score increases stack, so I'm going to follow the rules for stacking temporary hit points. That is, same source = "no stacking" but different sources stack. (That's also the same rule used for spells, I think.)

Now, down to the problem. Where do I register the "source" for determining stacking? What I mean is this:

• Is the monster ability the source? In other words, any time the monster ability is triggered, it's the monster ability that is the source, and therefore nothing will ever stack, no matter what hit it with lightning.
  
• Is the thing that triggers the monster ability the source? So a wizard casts Lightning Bolt, and a storm creature zaps the shambling mound with a natural shock attack, and a fighter uses one of those alchemical bottled lightning things to deal some electricity damage too... each of those a different source?
  

Thanks for your advice.

Before the FAQ about sources, it stacked.

Now, it shouldn't.

[outshyn]

Thanks guys. I just ended up creating a shambling mound "champion" that had a house rule to stack the CON.

Much appreciated!

[Losobal]

I can see why it shouldn't just from the perspective of..."so what, you keep casting some level 0 cantrip that does shock damage (piddly like 1d3, yeah there isn't a core one but it seems logical that if you can make acid, fire and cold with cantrips, you can do zappy too) and then the Shambling mound gains several hundred CON in the time it would take it to lose 1 point of CON?

[James Risner]

On of the cheese grinder scenarios is a SM on an electric plate. It starts with 9999 Con and gets a shock every round. The lowest I've seen a party get it is 99% health.